It's lunchtime at the Olympic Park and I'm sitting in a makeshift cafeteria in a huge white tent, feeling a little self-conscious.

The police and the army are sitting together. Close by, I can see the special-forces soldiers: you can tell them apart – men with thick necks and bulging muscles.

The caterers are wearing black; Locog officials are in cream trousers.

And then there's us, from G4S, in our lime green nylon T-shirts. We are the Millwall of the Olympics. We are the unpopular kids at school. Nobody seems to like us.

It's clear from the way the Locog guys look through us that the failure by G4S to provide enough properly trained security guards has not been forgiven, and it's also clear the G4S staff are being given all the worst jobs.

Resentment simmers just under the surface, bubbling over whenever the two groups have to work together. And the army can be a bit off too.

One soldier came up to me and asked: "Are you going to spit in my face and call me a baby-killer?"

The combination of petty rules, awful uniform and mild bullying is actually very reminiscent of school – except for the sniper on the roof of the Holiday Inn.

It is all a bit odd but, to be honest, I'm just happy to be here at all.

G4S screwed up my paperwork, along with that of thousands of others, and it looked as if I might never be deployed.

As I watched the opening ceremony on television, I wished I was in the park. Little did I know that in a few hours I would be.

With dozens of others, I got a call late on Friday, asking me if I was free to start work at 7am the next day.

Like the training beforehand, everything seems somewhat disorganised. On day one, I got to the park on time but had to wait two hours before anyone could find me something to do.

Not that I am complaining. I am not sure we would have been very good at it. At one of the quieter locations where a G4S team has been on the Rapiscan machine, they failed to spot half the fake guns, knives and homemade bombs that the computer throws in to keep staff on their toes. The tantalising sound of cheers filters out from some of the stadiums, but G4S people don't seem to be getting into them.

The security guards from our competitor Swords Security seem to be getting the best jobs inside the venues. It seems unlikely anyone from G4S will be offered any of those prized empty seats, either.

Perhaps it's Locog's way of punishing G4S for its ineptitude.

I'm given more training on the job, this time in body searches and vehicle searching. Neither is a role that I'm meant to be doing.

I was finally given a radio, but I wasn't shown how to use it, so I had to earwig on someone else who was having a lesson. It all feels a bit chaotic to me.

On one occasion I turned up for my shift on time, but all the jobs had already been allocated. More than 100 of us sat around for eight hours before a harried-looking G4S manager came in.

"How long have you been sitting here? Since 6am? I do apologise!" We're told we can either stay and be paid, or go home and come back tomorrow. To be honest, I'd had enough.